Currently, many researches are being conducted regarding technologies to provide various types of multimedia services including voice services and to support high quality and high speed data transmission in a wireless communication environment. For example, technologies associated with a Multiple-Input Multiple-Output (MIMO) communication system using multiple channels are in rapid development.
In general, a MIMO communication system utilizes a base station, and may be classified into a Multiple-User (MU) MIMO system comprising a plurality of users and a single base station, and a Single-User (SU) MIMO system comprising a single user and a single base station.
In a MIMO communication system, a base station and terminals may use a codebook. A certain space may be quantized into a plurality of vectors. The plurality of vectors generated by quantizing the particular space may be stored in the base station and the terminals as the codebook.
For example, each of the terminals may select any one matrix or vector from the plurality of matrixes or vectors included in the codebook, based on a channel that is formed between the base station and each of the terminals. The base station may also recognize the selected matrix or vector based on the codebook. The selected matrix or vector may be used for generating a transmission signal.
A number of studies have been made for a codebook used in a SU-MIMO system. However, there is need for a further study of a codebook used in a MU-MIMO system. For example, in a case where a cell of a base station includes a plurality of sectors, there is a need for an optimized codebook for use in a MU-MIMO system.